Analytical Sciences

Abstract − Analytical Sciences, 28(3), 243 (2012).

Substoichiometric Isotope Dilution Mass Spectrometry of Boron by the Ion-Pair Extraction with Halogenated Salicyl Alcohol Derivatives and a Quaternary Ammonium Salt
Keisuke MORITA and Hisanori IMURA
Division of Material Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa 920-1192, Japan
Novel salicyl alcohol derivatives (H2Xnsal), 5-bromo-, 3,5-dibromo-, and 3,5-diiodosalicyl alcohol which were abbreviated to H2Brsal, H2Br2sal, and H2I2sal, respectively, were synthesized and used for the selective extraction of boric acid. Boric acid was extracted with each H2Xnsal into chlorobenzene containing trioctylmethylammonium chloride (TOMACl) as an ion-pair complex, TOMA·B(Xnsal)2, at a different pH range. The extraction constant (Kex) of boric acid was determined by the equilibrium analyses including the formation of hydrogen-bonded complex of each H2Xnsal with TOMACl in the organic phase. The Kex values obtained by salicyl alcohol (H2sal) and its derivatives were decreased in the order of H2I2sal ≥ H2Br2sal > H2Brsal > H2sal. The most powerful extractant, H2I2sal, was employed for the substoichiometric extraction of boric acid, which was extracted at pH 5 – 9 with a substoichiometric amount of TOMACl in the presence of an excess of H2I2sal. The present substoichiometric separation method combined with the stable isotope dilution analysis using inductively coupled plasma mass spectrometry (ICP-MS) could be successfully applied to the determination of boron in a reference material of high-analysis compound fertilizer (FAMIC-A-08) without any correction as to the isotopic abundance.